I currently have a 40 gallon tank for my young beardie and use a 20" light fixture which houses an 18" Reptisun bulb. I have this situated right next to my heat lamp over his basking area. Would it be better for me to purchase a larger light fixture (say a 36" one being my tank is 36" long) or am I ok using what I currently have? I just want to make sure he recieves all of the UVB he needs
Well to recieve all the UVB waves which are essential to processing nutrients, you will have to get a longer bulb. It will have to be the same size of the tank. So I hope this has helped you. Oh the bulb should be on 12 hours to 14 hours a day. I have mine on at 9 AM and till 9 PM.
If you can afford it, go ahead and upgrade. The general rule is that the UVB should cover at least 2/3 of the tank, and your bulb only covers half.
That being said, as long as the UVB bulb is positioned close to the basking bulb, so that he gets both when he basks, he should be okay. The bulb is effective for about 6 months, so you could go ahead and use up the life of the bulb, and when replacement time comes, change to a longer bulb. I say this because I know what it's like to live on a tight budget, and although the 18" wouldn't be the most ideal, I really don't think he would suffer from it's use.
Ok, great, thanks alot for your replies. I will replace it with a proper size light when my budget allows. I do have the light right next to the basking spot, so hopefully he should be ok